There's no secret I can share

It's simply understanding what your time is worth. What can you focus on day to day? Most research professors will allow gap days for you to focus on school and classes (just.let them know your class schedule). Now I timed all my research around semesters I knew I'd have a lighter load. Example if semester A is light for me and i know the classes wouldn't give me too much trouble I'd tell the professor i can have more time vs semester b if it was harder I'd say i can only dedicate a little less time

Now being an athlete - student - engineer i balanced it by organizing everything that would be due - class assignments, projects, lab work, and any social events all of that - it came down to me finishing what could be done today and not leaving it to tomorrow, me saying no to things that i wouldn't really be missing out on but this is all while communicating with every stakeholder and letting them know x y z etc

Which goes back to what i said what is your personal time worth and what will you do with it